R is a highly extensible, open-source programming language used mainly for statistical analysis and graphics. It is a GNU project very similar to the S language. R’s strengths include its varying data structures, which can be more intuitive than data storage in other languages; its built-in statistical and graphical functions; and its large collection of useful plugins that can enhance the language’s abilities in many different ways.
R can be run either as a series of console commands, or as full scripts, depending on the use case. It is heavily object-oriented, and allows you to create your own functions. It also has a common API for interacting with most file structures to access data stored outside of R.
R’s biggest use case is performing statistical analysis and developing graphical representations. Its built-in packages allow for advanced statistical functions and simple graphic creation. With additional plugins, these abilities can become even more powerful and customizable. R also allows you to save your scripts and data when analyzing data, so that you can review and repeat analysis processes you’ve done in the past, whether to recreate results or check previous results.